Arthroplasty devices configured to reduce shear stress

ABSTRACT

Arthroplasty devices having improved bone in growth to provide a more secure connection within the body. Different embodiments disclosed include devices having threaded intramedullary components, devices configured to receive bone growth promoting substances, devices with resorbable components, and devices configured to reduce shear stress.

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims benefit from U.S. Provisional PatentApplication Serial No. 60/392,274, filed Jun. 27, 2002 which applicationis incorporated herein by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention is directed in general to arthroplastydevices and, in particular, to arthroplasty devices which improve bonegrowth into said devices.

[0004] 2. Description of the Related Art

[0005] The use of arthroplasty devices to replace damaged or defectivejoints within the body is commonplace in the medical field. Theprosthetic replacement of joints has evolved over the years from earlyrelatively crude models to current prostheses which closely replicatefunctions and motions of a natural joint. Prosthetic arthroplastydevices have been used as replacements for the shoulder, hips, knee,ankle and invertebral disc.

[0006] One problem encountered with prosthetic joints includes movementof the implant with respect to the patient's bones. This motion oftencompromises fixation. Another problem that occurs is an abnormal stresstransference from the implant to the bone.

[0007] The most common method of holding the implant in the bones is“press-fitting” the device into the intramedullary cavity of the bone.This often causes abnormal stress distribution, leading to prematurefailure.

[0008] These devices also rely on the ingrowth of the patient's bone tohold these devices in place. The difficulty of achieving true growth ofa patient's bone into a metal prosthesis is a well known problem in thesurgical field.

SUMMARY OF THE INVENTION

[0009] It is, therefore, an object of the present invention to providean arthroplasty device which has improved bone ingrowth capabilities.

[0010] It is a further object of the present invention to provide anarthroplasty device configured to reduce shear stress.

[0011] It is a still further object of the present invention to providean arthroplasty device having a resorbable component which restrictsmotion in a joint for a period of time to allow for improved boneingrowth.

[0012] It is a still further object of the present invention to providean arthroplasty device configured to receive bone growth promotingsubstances.

[0013] These and other objects and advantages of the present inventionwill be readily apparent in the description the follows.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is a lateral view, partly in cross section, of a femur anda prior art impacted femoral component of a hip replacement;

[0015]FIG. 2 is a lateral view, partly in cross section, of a femur andan embodiment of the present invention showing a femoral hip replacementdevice having a threaded component;

[0016]FIG. 3 is a cross-sectional view of the embodiment of the presentinvention shown in FIG. 2;

[0017]FIG. 4 is an exploded view of the device of FIG. 2;

[0018] FIGS. 5A-D, taken together, show the sequence of installation ofthe device of FIG. 2;

[0019]FIG. 6 is a lateral view, partly in cross section, of the deviceof FIG. 2 which includes a collared rod component;

[0020]FIG. 7 is a cross-sectional view of the device of FIG. 2 whichincludes an anti-rotation feature;

[0021]FIG. 8A is a cross-sectional view of the femur and anotherembodiment of the device of the present invention having an expandablecomponent shown in the contracted position;

[0022]FIG. 8B is a cross-sectional view of the device of FIG. 8A showingthe expandable component in the extended position;

[0023]FIG. 9A is a lateral view of another embodiment of the presentinvention;

[0024]FIG. 9B is a cross-sectional view of the device of FIG. 9A;

[0025]FIG. 9C is a cross-sectional view of another version of the deviceof FIG. 9A;

[0026]FIG. 10A is a lateral view of another embodiment of the presentinvention;

[0027]FIG. 10B is a cross-sectional view of the device of FIG. 10A;

[0028]FIG. 10C is a different cross-sectional view of the device of FIG.10A;

[0029]FIG. 11A is a lateral view, partly in cross section, of anotherembodiment of the present invention;

[0030]FIG. 11B is a lateral view, partly in cross section, of the deviceof FIG. 11A after a period of time;

[0031]FIG. 11C is a lateral view of another embodiment of the presentinvention;

[0032]FIG. 11D is a cross-sectional view of the device of FIG. 11C;

[0033]FIG. 11E is a lateral view of another embodiment of the presentinvention;

[0034]FIG. 12A is a lateral view of an alternative device according tothe present invention for use in prosthetic disc replacement shown inthe unassembled position;

[0035]FIG. 12B is a lateral view of the device of FIG. 12A in theassembled position;

[0036]FIG. 13 is a lateral view of a femoral component according to thepresent invention;

[0037]FIG. 14 is a perspective view of another embodiment of the presentinvention;

[0038]FIG. 15A is a perspective view of the device of FIG. 14 with aportion of the device removed and a syringe shown for injecting a bonegrowth promoting substance into the device;

[0039]FIG. 15B is a perspective view of FIG. 15A showing the device ofFIG. 14 partially filled;

[0040]FIG. 16A is a lateral view of a section of the spine showing thedevice of FIG. 14 installed in position between the vertebrae;

[0041]FIG. 16B is a lateral view of a drill bit which may be used tocreate a hole in the device of FIG. 14;

[0042]FIG. 17 is a perspective view of an alternative embodiment of thedevice of FIG. 14;

[0043]FIG. 18A is an end view of an alternative artificial discreplacement device for use in the present invention;

[0044]FIG. 18B is a sectional view of the device of FIG. 18A positionedbetween vertebrae of the spine;

[0045]FIG. 19 is a perspective view of an acetabular component for usein an embodiment of the present invention;

[0046]FIG. 20 is a perspective view of a femoral component for use in anembodiment of the present invention;

[0047]FIG. 21 is a perspective view of an alternative acetabularcomponent similar to the device of FIG. 19;

[0048]FIG. 22A is a perspective view of an alternative femoral componentsimilar to the device of FIG. 20;

[0049]FIG. 22B is a perspective view of another alternative femoralcomponent similar to the devices of FIG. 20 and FIG. 22A;

[0050]FIG. 23A is a lateral view of an alternative embodiment of thedevice of FIG. 12A;

[0051]FIG. 23B is a lateral view of the device of FIG. 23A shown in thedeployed position;

[0052]FIG. 23C is a lateral view of an alternative embodiment of thedevice shown in FIG. 23A;

[0053]FIG. 23D is a sectional view of the device of FIG. 23C;

[0054]FIG. 24A is an exploded view of an alternative embodiment of adevice according to the present invention;

[0055]FIG. 24B is a cross-sectional view of the device of FIG. 24A inthe assembled position;

[0056]FIG. 24C is a cross-sectional view of the device of FIG. 24Ainstalled in the femur;

[0057]FIG. 24D is a cross-sectional view of an alternative embodimentthe threaded component shown in FIG. 24A;

[0058]FIG. 25A is a cross-sectional view of a device according to thepresent invention installed in the tibia;

[0059]FIG. 25B is a cross-sectional view of an alternative embodiment ofthe device of FIG. 25A;

[0060]FIG. 26 is a cross-sectional view of a device according to thepresent invention installed in the proximal femur;

[0061]FIG. 27A is a cross-sectional view of a device according to thepresent invention installed in the distal femur;

[0062]FIG. 27B is a cross-sectional view of an alternative embodiment ofthe device of FIG. 27A installed in the distal femur;

[0063]FIG. 28A is an exploded view of a device according to the presentinvention for use in a long bone;

[0064]FIG. 28B is a cross-sectional view of the device of FIG. 28Ainvention installed in a long bone; and FIG. 28C is a cross-sectionalview of an alternative embodiment of the device of FIG. 28A.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0065] FIG 1. represents a typical prior art impacted femoral componentof a hip replacement commonly used in the surgical field today.Referring now to FIG. 1, there is shown a femoral component 10 having anelongated tapered portion 12, an extended stem portion 14 for connectingcomponent 10 to the prosthetic femoral head, and a textured surface area16. In use, tapered portion 12 is driven into a femur 20 which has beenprepared to receive component 10. Surface area 16 of component 10 isconfigured to encourage bone ingrowth to assist in the permanentattachment of component 10 within femur 20. Surface area 16 may containsmall beads, fibrillar wires or other structures known in the art topromote bone ingrowth. This type of arthroplasty device relies onimpaction of the device into patients' bones for stability.

[0066] The difficulty of achieving true growth of a patient's bone intometal prostheses is well known in the medical field. FIGS. 2-4 show adevice according to the present invention which assists in overcomingthis problem. Femoral hip replacement device, generally designated as30, includes an upper outer sleeve 32 which contains a textured surfacearea 34, a tubular inner component 36 having a threaded lower portion38, and an elongated rod component 42 having an outwardly extending stem44. In operation, threaded portion 38 of component 36 engages aninternally threaded area which has been previously incorporated intofemur 20. Alternatively, portion 38 may contain self tapping threads forattachment within femur 20. Sleeve 32 is then installed on the tubularportion of component 36 such that it is held against threaded portion 38and the inner walls of femur 20. Elongated rod component 42 is theninserted through tubular component 36 such that it is tightly held inplace by sleeve 32 and femur 20, as can be best seen in FIG. 2.

[0067] Although device 30 contains surface area 34 to assist boneingrowth, threaded section 38 helps to stabilize device 30, as threadedcomponents are less likely to allow motion between the device and bone.Bone ingrowth, which is dependent upon the surface features of thedevice and motion between the device and the bone, is thus facilitatedby decreasing motion between the arthroplasty device and a patient'sbone.

[0068] The process for installing device 30 is shown in FIGS. 5A-D.Referring now to FIG. 5A, a tap 50 having a thread cutting end 52 isused to chase threads within femur 20 in the area in which threadedportion 38 of component 36 is to be affixed within femur 20.Alternatively, portion 38 may be manufactured as a self-tapping device.After this has been performed, portion 38 is brought into threadedengagement with femur 20, with tubular portion 36 positioned above thethreaded connection (FIG. sleeve 5B). Next, outer sleeve 32 is forcedover tubular portion 36 until the edge of sleeve 32 contacts threadedportion 38 (FIG. 5C). Finally, elongated rod component 42 is insertedthrough tubular portion 36 captured within sleeve 32 such that outwardlyextending stem 44 is properly positioned for attachment within theprosthetic femoral head. This construction decreases the possibility ofmotion between device 30 and femur 20, potentially enhancing boneingrowth.

[0069]FIG. 6 represents another embodiment of device 30 which a collar60 positioned on rod component 42 between stem 44 and sleeve 32 to aidin the positioning of device 30 within femur 20. In this embodiment, rodcomponent 42 is inserted through tubular portion 36 within sleeve 32until collar 60 contacts sleeve 32. In this manner, forces within rodcomponent 42 are transferred to sleeve 32 having textured surface 34 forbone ingrowth, adding additional stability to device 30.

[0070]FIG. 7 is a sectional view of an alternative embodiment of device30 which adds an anti-rotation feature for additional stability.Referring now to FIG. 7, rod component 62 contains outwardly extendingedges 62 a, 62 b. Tubular component 64 contains a pair of channels 64 a,64 b within its inner walls corresponding to edges 62 a, 62 b. In thismanner, rod component 62 cannot rotate within tubular component 64,adding additional stability to the arthroplasty device, whichpotentially promotes bone ingrowth. Rod component 62 may also contain acruciform shape, with tubular component 64 having a corresponding shape.

[0071] Square threads, buttress threads, or reverse buttress threads maybe used in the embodiments requiring threaded devices, as these decreasehoop stress on the bone. Hoop stress can lead to fracture of the bone.Taper threads may also be used. In addition, the threads can be eitherleft or right handed.

[0072] FIGS. 8 A-B represent another alternative embodiment for anarthroplasty device according to the present invention. In thisembodiment, an adjustable component 68 having a first section 68 a and asecond section 68 b which are movable relative to each other by a pairof adjusting screws 70 is inserted into femur 20 in order to fit apatient's bone anatomy better. Screws 70 are adjustable to shiftcomponent 68 between a contracted position (FIG. 8A) and an expandedposition (FIG. 8B). Screws 70 are adjusted by a corresponding pair ofscrews 72 which, when turned, control the adjusting motion provided byscrews 70. Alternatively, a wrench may be used to turn a screw, or gear,which cooperates with a toothed component to force sections 68 a and 68b apart.

[0073] Component 68 is placed into the intramedullary canal of a boneand expanded. The tighter fit provided by component 68 decreases motionbetween the prosthesis and the patient's bone. Adjustable component 68also allows for compaction of the cancellous bone with the cortical boneinto which the prosthesis device is inserted. Cancellous bone is rich incells that promote bone ingrowth. Prior art impacted devices aregenerally inserted into the cortical bone after the removal of most ofthe cancellous bone. Thus, expanding components such as component 68will aid in the immobilization of the prosthesis and preserve thehealing characteristics of cancellous bone. While the device shown inFIGS. 8A-B show expansion of one component in one direction, multiplecomponents may be used that expand in multiple directions. A torquewrench may be used to control the force and help prevent fracture of thebone into which the device is to be inserted. In addition, shape memorymaterials may be used to change the shape of components within thedevice. For example, a sleeve made of nitinol could be inserted in itscontracted shape and then open to the expanded shape after insertioninto the base.

[0074] Alternative expansion mechanisms could be used for component 68.For example, a scissor jack-like mechanism or inclined planes could beused to move the sections to its expanded position. In addition,multiple sections can be used that expand in multiple directions.

[0075] In another embodiment, a rod component similar to that shown inFIGS. 2-6 is inserted between sections of component 68 in its expandedexpansion. The implanted rod may be held in position within component 68by adding a taper to the interior surfaces of sections 68 a and 68 b.

[0076] Upper outer sleeve 32 which contains textured surface area 34 inFIG. 2 can be adapted to further enhance bone ingrowth in devicesaccording to the present invention. FIGS. 9A-C demonstrate severalalternative embodiments which may be used to further promote thisgrowth. Referring now to FIG. 9A, upper outer sleeve 34 contains aplurality of wells 80 along its outer surface which replaces thetextured surface. Wells 80 are filled with collagen sponges 82 whichhave been soaked with Base Morphogenetic Protein (BMP). Sponges 82 areinserted into wells 80 prior to insertion of device 30 into femur 20. InFIG. 9C, sleeve 34 contains a plurality of channels 84 which extendalong the length of sleeve 34. In this embodiment, BMP could be injectedinto channels 84 after insertion of device 30, or BMP soaked collagensponges 82 may be forced into channels 84.

[0077] Another alternative embodiment of an arthroplasty deviceaccording to the present invention is shown in FIGS. 10A-C. A femoralrod component 90 having an outwardly extending stem 92 and a collar stop94 in installed through a sleeve 96 having a textured area 98 forpromoting bone ingrowth. The interior of sleeve 96 contains of pair ofgrooves 100 which correspond to a pair of wings 102 extending from theouter surface of component 90 such that the interaction of wings 102 andgrooves 100 allow small amounts of motion between rod component 90 andsleeve 96 to decrease the shear stress on textured area 98 where boneingrowth occurs. Shear stress can cause motion between the device andthe patient's bone, decreasing the chance of bone ingrowth. Devicesusing anti-rotation features, such as shown in FIG. 10C and FIG. 7, willhave rods with varying degrees of version, including antiversion andretroversion.

[0078] FIGS. 11A-E show an alternative embodiment of the deviceaccording to the present invention which uses resorbable components totemporarily decrease or remove the stress on the bone ingrowth surfacesof the device. Referring now to FIG. 11A, an arthroplasty device 100similar to the device of FIG. 10A-C is shown, having a femoral rodcomponent 102 with a outwardly extending stem 103, a positioning sleeve104 having a textured area (not shown) for promoting bone growth, and asolid disc 106 having an threaded outer surface 108. Disc 106 isinitially positioned within a femur 20. Disc 106 has been installed intoposition within femur 20, after its interior has been threaded in theappropriate area by using a tool similar to that shown in FIG. 5A.Alternatively, outer surface 10B may contain self-tapping threads.Resorbable material 110 is threaded into femur 20, contacting disc 106,and then rod component 102 is introduced into sleeve 104. Note thatcomponent 102 is supported by resorbable material 110 and not sleeve104. Preferably, device 100 contains the anti-rotation features shown inFIG. 10C. Additionaily, anti-rotation features can also be added betweendisc 106, resorbable material 110 and the end of rod component 102 foradditional stability. Suitable resorbable materials include a highmolecular weight poly-L-lactic acid (PLLA) polymers, calciumhydroxyapatite, tricalcium phosphate. Other potentially usefulresorbable materials include polydiaoxanone (PDS), oxidized regeneratedcellulose and various forms of collagen.

[0079] In this relationship, resorbable material 110 temporarilydecreases or removes the stress on the bone ingrowth surfaces of sleeve104. The forces on device 100 are transferred from resorbable material110 to the ingrowth surfaces of sleeve 104 as resorbable material 110disappears. Disc 106 may also contain a through hole 111 to aid in thedrainage of resorbable material 110. This resorption process generallytakes months. Bone will grow into the ingrowth area of sleeve 104 whiledevice 100 is supported by resorbable material 108. Eventual transfer ofthe forces to the ingrowth area of device 100 is important to preventbone resorption that occurs with stress shielding. Resorbable material110 may also temporarily eliminate movement through device 100.Eliminating movement across device 100 decreases forces on the boneingrowth surfaces. Motion through device 100 is permitted onceresorbable materials 110 has dissolved, as rod component 102 nowcontacts sleeve 104, as can be seen in FIG. 11B.

[0080] A prosthetic hip device according to the present invention isshown in FIGS. 11C-D. Hip device 112 includes a femoral rod component114 having an outwardly extending stem 115, a head 116 mounted on stem115, an inner acetabular component 117, and an outer acetabularcomponent 118. A resorbable component 120 is located between component118 and rod component 114 to restrict motion between the acetabular andfemoral components of device 112 until resorbable component 120disappears, allowing time for bone ingrowth to firmly take hold.

[0081]FIG. 11E shows prosthetic disc replacement device 122 according tothe present invention. Device 122 includes an upper plate 123 and alower plate 124 connected by a pivot 125. Resorbable material 126 isplaced between plates 123 and 124 before insertion of device 122 into aposition between vertebrae of the spine.

[0082] FIGS. 12A-B show an alternative embodiment of a prosthetic discreplacement device 130. Device 130 contains an upper plate 131 and alower plate 132. Each plate contains a keel-like ingrowth extensioncomponent 134 attached for rotation through plates 131, 132 at a pivot135. An activation device 136 consisting of a flat plate is also shown.To install device 130, the device is placed between vertebrae in thespine of a patient. Activation device 136 is pushed between plates 131and 132 to force extensions 134 away from plates 131, 132 to affixdevice 130 in its proper location between the vertebrae. Extensions 134are exposed to the cancellous bone of the vertebrae, immobilize device130 and help prevent its extrusion.

[0083]FIG. 13 shows another embodiment of a method for restrictingmotion of the prosthesis relative to the bone when using an arthroplastydevice. Referring now to FIG. 13, there is shown a femoral component 140positioned within femur 20. Component 140 is held firmly in place by afirst screw 142 which is affixed crosswise through component 140 andfemur 20. A second screw 144 is affixed through component 140 and femur20 in a direction oriented approximately 90° to first screw 142. A guideis preferably removably attached to femur 20 or component 140 to helpdirect a drill bit through femur 20 and to thread screws 142 and 144through the structure. Use of screws 142 and 144 assist in minimizingmotion of component 140 with respect to femur 20, allowing bone ingrowthbetween component 140 and femur 20.

[0084]FIG. 14 shows a device which promotes bone ingrowth in a spinalfusion procedure. Implant 200 consists of a box-like structure havingtop and bottom surfaces 200 a, 200 b, front and rear surfaces 200 c, 200d, and side surfaces 200 e, 200 f. In this embodiment, surfaces 200 aand 200 b are essentially parallel, 200 c and 200 d are essentiallyparallel, and 200 e and 200 f are essentially parallel; however, implant200 can consist of any shape which will fit between adjacent vertebrae.Surface 200 c contains an aperture 202 which allows access to theinterior of implant 200. Aperture 202 allows for the injection of a bonegrowth promoting substance into implant 200. Possible substances includePlatelet Rich Plasma (PRP), bone morphogenetic protein (BMP), orconcentrated leukocytes. Other substances which are available arediscussed in my co-pending patent application Ser. No. 09/897,000, whichapplication is incorporated by reference herein. Although implant 200 ispreferably manufactured from bone, it could also be constructed fromother compatible materials such as metal or polymers. Alternatively, themetal or polymer devices could be filled with bone.

[0085] FIGS. 15A-B show how implant 200 can be filled with anappropriate bone growth promoting substance. A syringe 206 filled with asuitable substance 207 is positioned with its needle 208 insertedthrough aperture 202. As syringe 206 is operated, substance 207 fillsimplant 200 with the bone growth promoting fluid, as can be seen clearlyin FIG. 15B. FIG. 16A shows implant 200 in position between adjacentvertebrae 210, 212 while syringe 206 injects growth substance 207 intothe implant.

[0086] A drill bit 216 is shown in FIG. 16B which may be used to createaperture 202 in implant 200. Bit 216 contains a smooth cylindricalsection 216 a, a fluted end 216 b having a point for drilling, and acollar stop 216 c. Drill bit 216 is particularly suited for drillingaperture 202 into implant 200, as collar stop 216 c acts to prevent bit216 from traveling too far into implant 200, possibly damaging thedevice. Drill bit 216 may be helpful when drilling aperture 202 into adevice such as implant 200 a, which has a different shaped structure, ascan be seen in FIG. 17. Aperture 202 can be aligned in any suitabledirection within the device. While aperture 202 can be drilled intoimplant 200 before inserting the device into position in the spine, itmay be advantageous to drill aperture 202 into implant 200 after it ispositioned between vertebrae 210, 212. This would avoid weakening ofimplant 200, as the device is under compressive forces when in position.Alternatively, implant 200 could be manufactured with aperture 202 inplace in the device.

[0087] Bone growth promoting substances can be used in many otherarthroplasty devices. FIGS. 18A-B show its use in connection with anartificial disc replacement (ADR) procedure. An ADR device 220 similarto the device of FIGS. 12A-B contains a pair of extensions 221 forfixing device 220 in the spine and a pair of end plates 222 a, 222 beach having an aperture 223. End plates 222 a, 222 b are separated by anactivating structure 226. End plates 222 a, 222 b may contain a seriesof channels which are connected to apertures 223. When device 220 hasbeen positioned in place between vertebrae 210, 212, syringe 206 can belocated with needle 208 inserted into apertures 223 of end plates 222 a,222 b to input growth substance 207 into device 220 to promote boneingrowth between the device and the vertebrae.

[0088] FIGS. 19 to 22A-B depict different arthroplasty devices which canbe used in conjunction with bone growth promoting substances to maximizebone ingrowth between the body and the implants. An acetabular componentfor use in hip replacement is shown in FIG. 19. Component 240 is acup-shaped device having a spherical outer surface 242 and a hollowcurved inner surface 244. A front surface 246 contains a plurality ofapertures 248. Apertures 248 are connected to a series of channels whichare connected to a series of outlets 250 which are scattered along outersurface 242 of device 240. When component 240 is placed in positionduring hip replacement surgery, bone growth substance 207 can beinjected into apertures 248 such that the substance can travel throughthe channels to outlets 250, where it can contact the hip bone topromote bone ingrowth between device 240 and the bone. An alternativeembodiment to implant device 240 is shown in FIG. 21. This acetabularcomponent 260 has a spherical outer surface 262, a hollow curved innersurface 264 and a flat front surface 266. Along the periphery of surface266 a series of grooves 268 are channeled into outer surface 262.Grooves 268 may be parallel channels along outer surface 262, or theymay spiral around outer surface 262. When component 260 is positioned inthe bone during hip surgery, growth substance 207 may be injected intogrooves 268 such that the fluid can flow between component 260 and thebone to promote bone ingrowth.

[0089] Examples of the present invention for use with femoral componentsare shown in FIGS. 20 and 22A-B. Referring now to FIG. 20, a femoralcomponent 280 is shown having a body 282 having an outer surface 283, aflat top surface 284, and an outwardly extending stem 286. A pluralityof apertures 288 are located on flat surface 284.

[0090] A series of channels within body 282 are connected to apertures288 at one end, while the other ends are connected to a series ofoutlets 290 located on outer surface 283. When component 280 isimplanted in position within a femur, bone growth substance 207 isinjected into apertures 288 such that it will travel through body 282and exit through outlets 290 between component 280 and the bone topromote bone ingrowth. Alternative versions of this device are shown inFIGS. 22A-B. In FIG. 22A, femoral component 280 a contains a body 282 ahaving an outer surface 283 a, a flat top surface 284 a, and anoutwardly extending stem 286 a. Along the periphery of surface 284 a, aplurality of grooves 292 are channeled into the outer surface 283 a.Grooves 292 may be straight along outer surface 283 a, or they canspiral around component 280 a. When component 280 a is fixed in placewithin a femur, growth substance 207 can be injected into grooves 292such that the fluid can flow between the implant 280 a and the bone topromote bone ingrowth. FIG. 22B shows a similar device 280 b, exceptthat grooves 294 are equally spaced around the periphery of uppersurface 284 b and are oriented in a parallel fashion along outer surface283 b.

[0091] The principles of the present invention taught in FIGS. 19-22Bcan be applied to other prosthetic devices such as knee replacements,shoulder replacement, and spinal fusion cages.

[0092] FIGS. 23A-D teaches several alternative embodiments of thepresent invention for use in spinal procedures similar to those taughtin FIGS. 12A-B and FIGS. 18A-B. Referring now to FIG. 23A, there isshown a spinal device generally indicated at 300 having a pair of endplates 302 a, 302 b. Each end plate contains a keel-like fixationcomponent 304 which is fixed for rotation about a pivot 306 through theinterior area of the end plate. Component 304 are offset from each otherwith respect to device 300 such that component 304 rest side by sidebetween end plates 302 a, 302 b when device 300 is in the unactivatedposition. This orientation allows for larger fixation components to beused in device 300 for better fixation in position between vertebrae. Anactivating component 308 is shown alongside device 300. Component 308consists of a pair of spherical pusher plates 310. In operation,activating component 308 is forced between end plates 302 a, 302 b,causing fixation components 304 to rotate about pivot points 306outwardly through end plates 302 a, 302 b, to extend from device 300 andholding the device firmly between vertebrae of the spine, as is shown inFIG. 23B.

[0093] FIGS. 23C-D show spinal device 300 a in which slots 316 areincorporated into end plates 302 a, 302 b such that fixation components304 rest within slots 316 when device 300 a is in the unactivated state.Slots 316, which may be shaped such that the end of each fixationcomponent 304 just fits within said slot, or may extend along a longerportion of each end plate, to allow for the use of a larger fixationcomponent with device 300 a, improving the holding power of spinaldevice 300 a when positioned between vertebrae.

[0094] FIGS. 24A-D show an alternative embodiment for an arthroplastydevice according to the present invention for use in hip surgery.Referring now to FIGS. 24A-C, there is shown a device 329 having afemoral component 330 with a outwardly extending stem 332, and a hollowpassageway 334 extending through the central area of component 330.Passageway 334 is square shaped in this embodiment, but it may be shapedin any configuration in which a component inserted into said passagewaycannot rotate, such as an ellipse, a triangle, pentagon, or hexagon.Component 330 also contains a recess 336 on its upper surface.Passageway 334 and recess 336 are connected by a channel 338. Anattachment component 340 contains an upper section 342 having a squareshape with a threaded aperture 344 at its upper end and a lower threadedcylindrical section 346. A screw 348 is also provided with the device.

[0095] To install femoral component 330 into a femur in a hipreplacement procedure, the inner surface of femur 20 is threaded at theproper depth using a tool similar to that shown in FIG. 5A. Attachmentcomponent 340 is installed within femur 20 by threading section 346 intothe femur. Component 330 is then located upon upper section 342 ofattachment component 340 by matching the shape of section 342 withrecess 334 in the proper orientation. Screw 348 is then inserted intorecess 336 of component 330 through channel 338 and threaded intoaperture 344 to hold the device in its proper position within femur 20.This procedure “pulls” the device into the femur, helping to preventfracturing the bone. A torque wrench may be used to adequately tightenscrew 348 to its proper tightness to prevent splitting femur 20.Attachment component 342 may be composed of a polymer such as carbonfiber, or alternatively may be composed of a resorbable material. Device329 minimizes motion between the implant and bone, as the matched shapeconnection between passageway 334 and upper section 342 of attachmentcomponent 340 allows for virtually no movement.

[0096] An alternative attachment component 340 a for component 340 isshown in FIG. 24D. Component 340 a contains a similar upper section 342containing a threaded aperture 344; however, lower cylindrical threadedsection 346 a contains a hollow internal section 352. Hollow section 352gives threaded section 346 a more flexibility than a solid component.Hollow threaded components and polymer threaded components are lesslikely to cause thigh pain from excessive stress transfer to the femurat the level of the threaded component. Furthermore, resorbablecomponents, in particular, are less likely to cause stress shielding ofthe proximal femur.

[0097] FIGS. 25A-B show an embodiment of the present invention for usein a prosthetic knee device. Device 400 includes a cylindrical component402 having a threaded outer surface and a recess 404 having a threadedinner surface. An articulating component 406 includes a planar section408 having an extension 410 with a treaded end 412.

[0098] To install device 400, the internal surface of tibia 416 isthreaded internally using a device similar to that shown in FIG. 5A atthe desired depth. Component 402 is then threadably engaged within tibia416. Articulating component 406 is then threadably affixed to component402 by threading end 412 of extension 410 into recess 404 until surface408 contacts tibia 416.

[0099] Referring now to FIG. 25B, prosthetic device 420 includes acylindrical component 422 having a threaded outer surface and anaperature 423 having a threaded inner surface, and an upper component424 having a planar surface 426 and an aperture 428 in the centralregion. The upper surface of component 424 is sized such that a cover430 may be snapped into position on the upper surface. Cover 430 may beconstructed of polyethylene. A bolt 432 having a head 433 is alsoincluded with device 420.

[0100] To install device 420, the internal surface of tibia 416 isthreaded internally using a device similar to that shown in FIG. 5A atthe desired depth. Upper component 424 is placed on the upper surface oftibia 416 and bolt 432 is placed through aperture 428 and is threadedinto aperture 423 of component 422 until head 433 contacts the uppersurface of component 424. Cover 430 is then snapped into position oncomponent 424.

[0101] In FIGS. 25A-B, components 402 and 422 may be composed of metalor a polymer, or could also be made from a resorbable material.Components 406 and 429 may be constructed from titanium or chromecobalt.

[0102]FIG. 26 shows a device 444 embodying the present invention for usein treating the hip socket. In this embodiment, a fracture 450 of afemur 451 is shown at the base of the femoral head 452. Device 444includes a femoral repair component 453 consisting of a cylindricalmember 454 having a threaded end section 456. Component 453 alsocontains an aperture 458 which is oriented angularly toward femoral head452. Aperture 458 may be threaded internally. A second component 460 ofdevice 444 consisting of a connecting rod 461 having a threaded end 462is connected to femoral head 452 by a threaded aperture 464 withinfemoral head 452.

[0103] To install device 444 for repair of the fractured femur, threadedend section 456 is located within femur 451 using the techniquespreviously discussed. The correct angular position of component 460relative to component 453 and femoral head 452 is determined, andthreaded end 462 is affixed within femoral head 452. Rod 461 is sizedsuch that the end can be inserted into aperture 458 of component 453using a small amount of force to overcome the friction fit between thecomponents. Rod 461 is then inserted into aperture 458 until femoralhead 452 is positioned against femur 451. The interaction between rod461 and component 453 acts to hold head 452 in the correct position toheal.

[0104]FIG. 27A-B show an embodiment of the present invention for use inrepairing a fracture of the distal end of the femur. Repair device 480includes a component 482 having a solid first section 484 with athreaded outer surface and a narrower cylindrical second section 486. Toinstall repair device 480, the internal surface of femur 488 is threadedat a section on the opposite side of fracture 490 from distal end 492 offemur 488 using a device similar to that shown in FIG. 5A. Threadedsection 484 of component 482 is affixed within femur 488 such thatsection 486 is spaced apart from distal end 492 of femur 488 when thetwo sections of femur 488 are held together tightly along fracture 490.A hole 496 is then drilled across the distal end 492 of femur 488,passing through section 486 of component 482. A screw 498 is then placedinto hole 496, passing through section 486 of component 482 and isthreaded into femur 488 as shown at 500. This device holds the sectionsof femur 488 tightly together to aid in the healing process. Threadedsection 484 can be made from a resorbable material, non-resorbablepolymers, metal, or a combination of materials. For example, section 484could be made with a metal core surrounded by a resorbable component.

[0105] The device 480 a of FIG. 27B is similar to device 480 shown inFIG. 27A except for the design of component 482. Component 482 a isconstructed like the component shown in FIG. 24D in that first section484 a is hollow with a threaded outer surface. As discussed previously,the hollow section allows more flexibility than a solid component. Theinstallation of device 480 a follows the same methods of that taught fordevice 480.

[0106] FIGS. 28A-C show a fixation device 500 for use in long bones.Referring now to FIG. 28A, a first component 502 contains a solidcylindrical portion 504 having an outer threaded surface 506, and acylindrical portion 508 having a lesser diameter than portion 504 andcontaining a threaded portion 510 located along its length. A secondcomponent 512 comprises a cylindrical disc having a threaded outersurface 514 and a central aperture 516 which is threaded. In addition, apair of screws 520 are provided.

[0107] Fixation device 500 is shown on its installed position in FIG.28B. A long bone 540 is shown having a fracture 542. Threads are made onthe internal surfaces of bone 540 in the appropriate positions in themanner previously described. Component 502 is then positioned within theupper section 540 a of bone 540 by engaging outer threaded surface 506into the threaded position in section 540 a to fix component 502 in itsproper location. Component 512 is then positioned onto threaded portion510 of cylindrical portion 508 while component 512 is being threadedinto lower section 540 b of bone 540. Component 512 is rotated until itis firmly coupled to both component 502 and bone 540. In thisembodiment, left handed threads may be used for threaded 510 and alsofor threaded outer surface 514 and threaded aperture 516. In thismanner, the action of installing component 502 of device 500 acts topull the components together. After device 500 has been installed inbone 540, holes may be drilled into upper section 540 a and lowersection 540 b through the upper and lower ends of component 502 andscrews 520 inserted to prevent rotation of long bone 540 about device500.

[0108]FIG. 28C shows device 500 installed within long bone 540 withoutthe use of screws 520.

[0109] Another embodiment for use with the arthroplasty devicesaccording to the present invention involves the use of bone cells. Boneand bone cells are grown onto the prosthesis prior to implanting thedevice into a patient. To accomplish this task, bone cells are initiallyharvested from a patient. Osteoblasts could be harvested from apatient's iliac crest; a piece of iliac crest bone could be surgicallyremoved. In “Culture of Animal Cells” by R. Ian Freshney, Wiley-Liss NewYork 2000, which is incorporated herein by reference, techniques forharvesting osteoblasts are described on pps. 370-372. Also described inthe article are cell culture techniques. U.S. Pat. No. 6,544,290, whichissued on Apr. 8, 2003, to Lee et al, which patent is herebyincorporated by reference, teaches a method culturing cells onto aresorbing calcium phosphate material. The present invention contemplatesthe culturing of cells onto arthroplasty devices made of titanium,chrome, cobalt, ceramic, or other non-resorbable materials.

[0110] In the present invention, bone is harvested from a patient, andthe bone then treated to remove the cells. The cells are cultured andgrown onto the prosthesis in a lab. The device, now covered with livingbone cells, is subsequently implanted into the patient. These cells,which include osteoblasts, osteocytes, donor bone cells, stem cells orother pluripotential cells, and other cells that are capable oftransforming into osteoblasts or osteocytes, will promote the boneingrowth to improve the stability of the device in the body.Alternatively, the bone cells could be added to the device at the timeof surgery.

[0111] To foster the improved bone ingrowth, the titanium componentswould have surface treatments. For example, the surfaces could beporous, beaded, plasma sprayed, or covered with fibrillar wire topromote ingrowth. Alternatively, the cells could be cultured ontoarthroplasty devices made of other metals, or materials such as ceramicand hydroxyapatite coated metals. In addition, to attempt to improve theingrowth characteristics of this process, bone growth promotingsubstances such as TGF-α,-β1, -2; EGF, IGF-I; PDGF, FGF, BMP-1, VEGF andother similar substances may be added to the cell culture medium.

[0112] It is contemplated that features of the various embodiments maybe combined. For example, the expandable component taught in FIGS. 8A-Bcould be used with the threaded component of FIGS. 2-7. Also, althoughthe drawings are directed primarily to the use of the invention inprosthetic hips, the principles may be applied to other prostheticjoints, such as knees, shoulders, ankles and wrists. In addition, bonecells harvested from the patient could be added to the bone growthpromoting substance used in other embodiments. These cells could also becombined with a cell culture media or a synthetic matrix.

[0113] While the present invention has been shown and described in termsof preferred embodiments thereof, it will be understood that thisinvention is not limited to any particular embodiment, and that changedand modifications may be made without departing from the true spirit andscope of the invention as defined in the appended claims.

What is claimed is:
 1. A prosthesis for implantation into a bone,comprising: a sleeve having an inner passageway containing a centralopening with at least one channel located on the periphery of saidcentral opening, and an outer surface, sized to fit tightly within thebone, containing at least one section contacting the bone, said sectionhaving a textured surface to promote bone ingrowth; and a rod componentcomprising an elongated shank having an outer surface extending betweena proximal end and a relatively narrow distal end, with at least aportion of said shank having at least one lobe extending therefrom, saidportion of said shank sized to fit within said inner passageway of saidsleeve; wherein when said rod component is inserted through said sleevewhich has been inserted tightly into the bone, the interaction betweensaid lobe of said shank of said rod component and said channel withinsaid sleeve allow for a small amount of rotation, thus reducingtensional shear stress between said prosthesis and the bone.
 2. Thedevice of claim 1 wherein said textured surface comprises an array ofbeads.
 3. The device of claim 1 wherein said textured surface comprisesan array of fibrillar wires.
 4. The device of claim 1, wherein said rodcomponent contains a collar stop for contacting said sleeve.
 5. Thedevice of claim 1, wherein said sleeve contains a plurality of channelson the periphery of said central openings and said rod componentcontains a plurality of lobes along at least a portion of said shankcorresponding to each channel.
 6. The device of claim 5, wherein thecross section of at least a portion of said slave and said rod componentform complementary cruciform shapes.
 7. The device of claim 1, whereinsaid bone contacting section of said sleeve contains a bone growthpromoting material.
 8. The device of claim 7, wherein said bone growthpromoting material comprises bone morphogenetic protein (BMP).
 9. Thedevice of claim 7, wherein said bone growth promoting material comprisesplatelet rich plasma.
 10. The device of claim 1, wherein said devicecontains a rod component having varying degrees of version.
 11. Thedevice of claim 10, wherein said version comprises antiversion.
 12. Thedevice of claim 10, wherein said version comprises retroversion.